The herring run on the Merrimack River is the best in two decades – but why?

Herring and/or alewife, which like salmon is an anadromous species (spawn in fresh water, live in salt water), are returning to the Merrimack River this year in numbers not seen since the early 1990s. Nobody knows why, just as we’re not sure why the numbers crashed in the past decade, but it’s kind of cool.

Read about it in the Monitor, with a lot of excellent photos showing how fish are trucked around dams.